1. Field of the Invention
The present invention relates to a shock absorbing propeller shaft apparatus for a motor vehicle.
2. Description of the Related Art
As a shock absorbing propeller shaft apparatus for a motor vehicle, there is a structure in which first and second propeller shafts are coupled by a constant velocity joint, an inner shaft end is provided in the first propeller shaft, a tubular outer shaft end is provided in the second propeller shaft, and the inner shaft end of the first propeller shaft is fitted to the tubular outer shaft end of the second propeller shaft via the constant velocity joint, as described in Japanese Patent Application Laid-Open No. 2008-132952 (Patent Document 1).
In this shock absorbing propeller shaft for a motor vehicle, the inner shaft end in the first propeller shaft is spline-fitted to an inner race of the constant velocity joint and is locked in an axial direction. If a vehicle comes into collision, the inner shaft end of the first propeller shaft moves backward, and the inner race of the constant velocity joint provided in the inner shaft end in the manner mentioned above moves to a sliding motion limit position (a closed end of a race groove) in the tubular outer shaft end of the second propeller shaft. Then, the locking in the axial direction mentioned above between the inner shaft end and the inner race is exposed to a load so as to be released, and the inner shaft end moves further backward while leaving the inner race within the tubular outer shaft end, and absorbs a shock caused by the collision.
In this case, in the shock absorbing propeller shaft apparatus for a motor vehicle, a shock absorbing portion is formed in the tubular outer shaft end of the second propeller shaft, and a leading end of the inner shaft end mentioned above moves further backward while leaving the inner race within the tubular outer shaft end, breaks the shock absorbing portion and further absorbs the shock caused by the collision.